Right-of-way telephone system



c. s. RHOADS RIGHT-oF-WAY TELEPHONE SYSTEM Filed Aprill 29, 194s April4, 1944.

III-II" mvENToR 4 jhoad TToRNEY Patented Apr. 4, 1944 UNITED `sTATlSzslafrrrlyr OFFICE RGHT-OF-WAY TELEPHONE SYSTEM Charles Stanley Rhoads,Albany, N. Y., assgnor to American Telephone and Telegraph Company, acorporation of 'New York Application April 29, 1943, Serial No. 484,956

11 Claims.

This inventiony relates to telephone systems. More particularly thislinvention relates to switching apparatus for telephone systems. Stillmore particularly, this invention relates to arrangements for enabling aparty to seize a busy line and permit him to signal over the line. I

When a telephone omce such as community dial office and a telephoneoiiice such as an'operator or master oce are arranged to render serviceto telephone subscribers, a number of trunks are interposed between thetwo offices so that the subscribers in the communityidial area, forexample, may communicate ,with subscribers in the area of the operatoror master oiice. In an emergency it may happen that an urgent call mustbe made by one of the conimunity dial office subscribers to the operatorat the operatory or master oice or to a subscriber in the latter areabut all trunks between the two offices may be busy at that time. It isalso possible that all links or switches in the lcommunity dial oicearebusy. In that event the urgent call must await the liberation of one ofthe several trunks or links or switches. Any such delay may perhaps bequite unfortunate;

In order to overcome the `tliliculty referred to, and to provide servicein any such emergency, it is proposed to set up apparatus at the4community dial office and at the operator or master oliice to enable asubscriber to seize one of V the trunks-which may be a preassigned trunkwhen the trunk is busy, interrupt whateverex isting service there may beover the seized trunk, and connect the subscribers set to thatV trunk.This arrangement will connect the subscriber to the operator at themaster (orroperator) oice and so permit the subscriber .to communicatewith the operator during the period of emergency.

In accordance with this invention lthe subscriber who is to be permittedto seize an assigned trunk will have a magneto generator connected toone of the conductors of his linewhich,wh en1op erated, will rire a gastube at the dial office.V The ring of the gas tube will set certainrelay apparatus into operation to interrupt existing servlamp or otherindicating device may be employed l at the master cfce to apprisel theoperator that a call is being made over the trunk. y

The proposed arrangement thus will give rightof-way to a subscriber at atime when all lines, links or switches are busy. The apparatus're- `costand may be of value for use in emergency conditions.

master` or operator oice MO by a plurality of .trunks TKi, TK2.

There are in general more subscribers lines, such as SB1, extending tothe `ofce CDO than there are trunks, 'such as TK1 between the oice CDOand the oce MO. It is well known in the art that any subscrbers linesuchas SB; or SBz may be connected to any one ofl the trunks such as TKior TKz through the equipment at the community dial oce CDO and ftliatsignaling may take place over any one of the lines and any one of thetrunks in tandem.

For example, when the telephone receiver TR of the subscribers set SS;is removed from its Shook, the line relay L at the community dial oiceCDO will be operated over a circuit including battery, the upper windingof relay L, the upper armature and back contact of the cut-off relay CO,

thejupper conductor of the subscribers line SE1,

30 the pulsing contact PC of dial DL, the transmitter TT,' theswitch-hook SH, the winding Pof the induction coil, the lower conductorof .line SBi,

`lthe lower armature and back contact of the cutoi relay CO, the lowerwinding of relay L, rectier Z and ground. VThe closure of the contact ofrelay L operates the line linder start circuit 'so -that va line finder(not shown) may be actuated to nd the calling line. As is well known,when the calling line is found, ground is applied to the sleeve contactS, whereupon the cut-oir lrelay CO becomes operated by the completion ofian ObviousY circuit. connects the windings of relay L from thecallfing" subscribers line SBi. plied in a well known manner' throughthe line .'nder from4 its associated first selector (not The cut-01Trelay CO dis- Dial tone is also apshown) to the subscribers line'SBito'inclicate to the subscriber that the apparatus is ready for dialing.The subscriber may then dial the deysired number and talk over the linelindercrcuit for outgoing'calls, as is well known. The fout- `going callmay be completed over. any one of the various trunks, such as TKiwhichmay happen to be selected by the dialomcev equipment. f While quired topractice the invention is simple, of low 55 theVA subscribers line ,SBrmay'be'connected to a trunk such as TKi, for example, other Subscriberslines may be connected to other trunks either for incoming or outgoingcalls.

Suppose, however, that the dial DL of the subscribers set SSi isoperated to dial or some` other preassigned code to reach the operator(at the master cnice MO). The dial office equipment will hunt over thegroup of trunks assigned to that level in a well-known manner and if allof the trunks or all switch paths are busy, the trunk hunting selector(not shown) will return a busy tone to the subscriber. Under suchconditions it it possible to signal the operator in accordance with thisinvention by operating-a-handfgenerator MG at the local station.Thegenerator -MG controis a gas tube TB at the oilce CDO and otherequipment employed for seizing a predetermined or preassigned trunk suchas TK1, disconnecting all service over that trunk, and rendering thetrunk busy to all parties except the one operating the hand generatorMG. The subscribers telephone transmitter TT and receiver TR will beconnected'to the trunk TK1 to enablethe subscriber to communicate withthe operator or other desired party. This will now be explained in vgreater detail.

The hand --or magneto vgenerator MGmay be operated by the subscriberwhile his receiver TR is retained on the switch-hook SH. When operatedthe generator MG supplies a lsubstantial alternating voltage to theupper or tip conductor T of line SBr, this alternating voltagebeing'applied over a circuit'including the upper armature of relay CO,the'control electrodes of tube TB, the battery KS, and ground. Thealternating voltage of generator MG'and thevoltage of lbattery KStogether are suicient'tore'the*tube TB, that is, to ionize the gaswithin tube TB. When tube TB 'is fired, the relay A will'be operatedovera circuit which'includes battery KS, the left-hand winding of relayA, the anode and upper control electrode of tube TB, the'upper armature'of relay CO, the upper or tip conductor T of line SB1,the generator MGand ground. As the left-handwinding of relay A becomesenergized tooperate'the relay, relay A will'become'locked in its operated positionover a circuit which includes the armature and contact of relay A, theright-hand winding of relay A, the makeebforebreak contact of relay C,the winding of relay B, battery and ground. Thus,v relay A will beoperated in response tothe reception of the a1- ternating wave ofgeneratorMG and it will be locked in its operated position.

It will be observed that the winding of relay B is included in thelocking circuit of relay A. Consequently relay B will be operated inresponse to the operation of relay A. The opening of the back contactsof the three upper armatures of relay B will disconnect the trunkhunting selector multiple tip T, ring R and sleeve S arch from the trunkTK1. The uppermost armature of relay B will be connected to the tip T orupper conductor of the subscribers line SB1 and thereby establish aconductive path between the upper'or tip conductors of trunk 'IKi andline SBl. The next uppermost armature of relay B will`be connectedthroughthe winding of relay lC to the ring R or lower conductor of lineSB1 and thereby establish a conductive path between the lower or ringconductors of trunk TKi and line SBi. The trunk TK1 will thus beelectrically connected to the subscribers line SB1.

The closure of the contact of the lower inner armature of relay B inresponse to the voperation of relay B will apply ground to the sleevearc S of the trunk hunting selector multiple so that this trunk TKi willtest busy for all subsequent outgoing or incoming calls. This sameground will be applied to the upper terminal of the winding of thecut-oi relay CO, causing relay CO to operate. The operation of relay COwill remove the subscribers line S131 from the line finder start circuitand thus prevent actuating a line finder when the subscriber on line SBiremoves his re- ,ceiver from the switch-hook. Ground on the sleeveconductor is also extended to the connector mul-tiple to preventincoming calls from being completed over the subscribers line SB1. Thetwo lower-outer armatures of relay B will dis.- connect-the incomingselector from the operators circuit (or other line circuit) connected totrunk 'IKi and interruptany call being made over this circuit.

The lower or ring conductor R of line SB1 is 'shown connected to themake contact of the upper intermediate'armature -of relay B through thewinding of relayvC. While Arelay B remains operated, I current will`iiow `through the winding of -relay C to-hold it operated. Thearmatureof relay -C applies ground to the winding of relay B to hold relay Boperated. Inasmuch as relay C is 4of theslowrelease type, relay vC willhold relayrBoperated oven when the subscriber moves his-switch-hook SH`back and forth to ilash the operator. Moreover the operation ofrelay-Cwill open thelocking-.circuit of relay Aand allow relay `A torelease without .causingrelay :B '.to release.

Ithasbeen :pointed out that Yby operating generator .MGfthe relay Bbecomes operated to Yinterconnect the subscribers line SB1 With-trunkTKl. Uponfthe completion of this-interconnected vcircuityrelayM'R at.the'master office NIO, which is-connected lto vtrunk TK1, will 'becomeoperated because the winding of this relay is included in -theinterconnected circuit. Upon the operation .of relay MR, the trunk lampTL will be illuminated to attract the operators-attention. The operatorlmay then insert lher 4plug P1 into jack J; toanswer .the call. Theinsertion :of plug'Pl into jack J1 will cause vrelay MR to release andthereby extinguish lam-p TL. At the same time the Winding of lthesupervisory relay SR of the operators cord circuit will be energized-and relaySRwill 4remain renergized as longas thereceiver TR at Vthesubscribersvset SS1 is removed from its switch-hook SH.

The winding of relay FR is included inseries with the sleeve contacts ofVVplug P1 and jack fJ1.and resistanceY. Relay FR willfthereforebeoperated .as .soon as the operator insertsher plug P1 into jack J1. If'in the `meantime the subscriber moves ,his switch-'hook SH back 'andforth to attract the operatorsattention, the relay SR Willbe releasedwhen the circuit is brokenby the switch-hook SH and re-.operated when,the circuit is recompl'eted. `When vthe lback contact of'relaySRkisclosed upon the Vrelease of relaySR,`t`ne supervisory lamp `SL willbeilluniinate'dfby lthe'completion .of a circuit whichincludes battery,lamp vSL, 'f the armatureandmake contactfof relay FR,`the 'armaturean'dbac'kcon- -tactof relay SR and ground. Thelamp SL will beextinguished whenever relay .SR releases. Hence lamp [SL .will Yberepeatedly flashed `lto notify the operator that ,the subscriberdesires'to communicate with her. YThe ,operator of .course may connectthefsubscriber v.to any other party.

When ,lines .SBi and TK1 are interconnected las* alreadydescribed, thesubscriber maytalk vto the operatoror to any other party connected tothe line by the operator. The talking path is a normal two-way path fromwhich alllpreviously connected lines have been disconnectedj Theinterconnected circuit is also held busy for all f will then be free foruse by .any other subscriberi' subscriber a right-of-way not heretoforeprovided*` in telephone systems. The additional equipment required topractice the'invention is simple and readily available and its initialcost as well as the cost of maintenance are quite small. The

operation and control of the apparatus in re-' sponse to the subscribersmanually operated generator MG is positive and free from anyinterference either by the operator or by the other subscribers.Moreover, the seizure of trunk TKi is accompanied by secrecy in that allother subscribers of the omce CDO are disconnected from trunk 'IKi andcannot hear the conversation thereover. The value of the arrangementduring emergencies is considerable. Because of its simplicity thearrangement can be easily` applied to many types of telephone systemswith very little modification.

Although the magneto generator MG is shown connected to one of theconductors of the subscribers line SBi, it does not vary the impedanceof the line or affect transmission over the line while it is unoperated.As is well known the magneto-generator becomes effectively connected tothe line only during the timein which the crank handle is rotated by thesubscriber. Although the generator is associated with the subscribersset SSi, similar generators may be associated with other of thesubscribers sets, but each such generator will require apparatus torespond to the generated current to interrupt service over other of thetrunks and at the same time to render the interconnected lines andtrunks assigned for seizure busy Although gas tube TB is also connectedto the subscribers line SBi, the tube has no effect upon transmissionuntil the gas enclosed within its envelope becomes ionized. The gasbecomes deionized as soon as the crank of the generator is stopped.

The device Z is inserted in series with the winding of line relay L sothat only unidirectional current may flow therethrough. Because of itsunidirectional characteristic, alternate halves of the current generatedby the magneto device MG will traverse the device Z. The device Z willtherefore substantially reduce any flutter of the armature of relay Land prevent false operation of the apparatus controlled by the relay L.The device Z will also serve to conne practically all of the generatedalternating voltage to the gas tube TB to aid in ring the tube. Any wellknown ,of the appended claims.

rectieror-varistor may be used for this purpose. A thermistor may lalsobe used for this purpose, but the thermistor will operateto reduce:flutter by means' of its slow-actingcharacteristic.

The gas tube TB is shown connected to the tip conductor Tlof line SB1between the upper armature ofrelay CO and the upper Winding of relay L.The Itube is therefore disconnected from the generator MG after therelay CO has operated to prevent its occasional false operation. Ifdesired, the tube may be connected between the upper or tip conductor Tof line SB1 and the upper armature of relay CO` In the latter positionthetube will be connected to generator MG even after relay CO hasoperated.

. Although this invention hasv been shown. and

described in: certain particular arrangements merely for illustrativepurposes, it willbeunderstood that thisinvention may be appliedto otherand widely varied organizations Without departing fromthe spirit of theinvention and the scope What is, claimed is: Y

1. The combination of a central ofce, 2 rst subscribers circuitconnected by a telephone `lirie to the central cnice, a secondsubscribers circuit, means for enabling the second subscriber to'seiz'ethe telephone line extending to the'rst subscriber, said means includinga gas tube Vat the central office, means controlled 'by the4 secondsubscriber to re the gas tube, and means responsive to the firing of thegas tube to discon nect the iirst subscribers circuit from the telephoneline and substitute the second subscribers circuit therefor.

2. The combination of two telephone oiiices, a .plurality of trunksinterconnecting said oiices, means for enabling a subscriber to one ofsaid offices to communicate with the other oiice over a predeterminedone of said trunks, said means comprising a generator to be operated bysaid subscriber, a gas tube connected to said generator and fired whensaid generator is operated, and means including a relay responsive tothe firing of said tube to seize said predetermined trunk and tointerrupt all other service over said trunk.

3. The combination of an operator cnice, an auxiliary ollce, a trunkinterconnecting said offices to Which telephone subscribers may haveaccess, a gas tube, means to re said gas tube and seize said trunk topreempt it for use by a particular subscriber, said means includingmeans to interrupt service by all other subscribers over said trunk.

4. The combination of a main oce, an auxiliary office, a lineinterconnecting said omces,

n means for preempting service over said line, said preempting meansincluding a gas tube, and means responsive to the firing of said tube tointerrupt any existing communication over said line.

5. The combination of two telephone omces interconnected by a line overwhich communication normally takes place, a gas tube, a relay controlledby said tube to interrupt service over said line, and means for firingsaid tube.

6. 'I'he combination of two telephone oices interconnected by a linewhich is available to numerous subscribers of said offices forcommunication purposes, means for interrupting any existing service oversaid line and seizing it for use by a particular subscriber, said meanscomprising a source of potential, a relay controlling said line, andmeans including a gas tube respon...

-sive .to the potential .-of fsad source ,ffor iiringzsaid gas tube and-operating saidrelay.

7. The combination l'oifan yoperator cnice, an auxiliary office, -a-.trunk -line extending wto rsaid operator cnice, ya plurality fofsubscribers lines each of whichz'may ,Abe connected :to said .trunkline, Vmea-ns to .fenable a :subscriber :to seize said trunk -linewheniit Ais busy ,and connect Ahis own line thereto, :said means:including :afsource ,of voltage supplied from fone of said subscriberslines,:a `gas :tube controlled. by said sourcefof voltage, and meanscontrolled-'by said ggasftube to render said trunk .line V:busy :to`:all :subscribe-rs .lines except the subscribers iline which `:suppliessaid source of voltage.

`8.In a signaling system, .the .combination of rst .and second stationsconnected -to eachother by aflineso as to v'be :in communications witheach other, sa ,third ystation,means'ito connect said lsaid potential tointerrupt communication between said 'first and secondstations.

'9. In a signaling system, the combination of a .central station,aplurality o'f auxiliary stations, a line terminating Vatsaid centralstation, means for connecting any ,one of said auxiliary stations to-Vsaidlineto establish communication With thevcentral station, means atone of said auxiliary stations lfor seizing said line for communicationvto said central station, said means including meansfor producing-apotential of predetermined magnitude and means responsive to saidpotential for interrupting `communication over said line andforpreventing any of the other auxiliary .stations from being connectedto said line.

r1.0. The combination of Va plurality of trunks interconnecting twotelephone oices, means for seizing a predetermined one of said trunkswhether :or not thatitrunk .or all other trunks are vlousyfsaid `meanscomprising a source of voltage,

algas tubecontrolledby the voltage of said source,

yand vapparatus controlled by saidgas tube to seize said Ipredeterminedtrunk.

11. The "combination of two 'oilices connected to each other bya linefor signaling purposes, said line being available to various parties atlsaid ofces for signaling purposes, means for preempting said line torender said line available for special service with lprivacy whether ornot said line 'is busy, said means including a gas tube, means to firesaid gas tube, and means responsive to .theflring of said gas tubetopreempt said line for said special service.

CHARLES STANLEY RHOADS.

